A Danish Twin Study of Schizophrenia

Margit Fischer; B. Harvald; M. Hauge

doi:10.1192/bjp.115.526.981

A Danish Twin Study of Schizophrenia

The British Journal of Psychiatry ◽

10.1192/bjp.115.526.981 ◽

1969 ◽

Vol 115 (526) ◽

pp. 981-990 ◽

Cited By ~ 45

Author(s):

Margit Fischer ◽

B. Harvald ◽

M. Hauge

Keyword(s):

Environmental Factors ◽

Twin Study ◽

Genetic Factors ◽

Concordance Rate ◽

High Concordance ◽

Danish Twin

Previous studies on schizophrenia in twins have quite recently been reviewed in detail by Gottesman and Shields (1966a) and Shields (1968). The indications of concordance in different series are highly diverging, in monozygotic pairs ranging from near unity to zero. The high concordance rates found by Luxenburger (1928), Kallmann (1946) and Slater (1953) stress the importance of genetic factors in the aetiology of schizophrenia, whereas the low concordance rate in two recent Scandinavian twin series (Tienari, 1963; Kringlen, 1966) has given rise to the question whether special genetic or environmental factors prevail in some populations. It has, therefore, been found of interest to study schizophrenia in a Danish twin population.

Download Full-text

The Nature and Origin of Common Phobic Fears

The British Journal of Psychiatry ◽

10.1192/bjp.134.4.343 ◽

1979 ◽

Vol 134 (4) ◽

pp. 343-351 ◽

Cited By ~ 156

Author(s):

Svenn Torgersen

Keyword(s):

Environmental Factors ◽

Social Adjustment ◽

Twin Study ◽

Genetic Factors ◽

Factor Analyses ◽

Factors Affecting ◽

Five Factors

SummaryBy means of a twin study an attempt was made to throw light upon the aetiology and nosology of phobic fears. Factor analyses revealed five factors, namely separation fears, animal fears, mutilation fears, social fears and nature fears. The study demonstrated that, apart from separation fears, genetic factors play a part in the strength as well as content of phobic fears. Environmental factors, affecting the development of dependence, reserve and neurotic traits generally, seemed also to be of some importance. It was further demonstrated that phobic fears were related to emotional and social adjustment and this was true to an even greater extent for separation fears.

Download Full-text

Muscle Dissatisfaction and Muscle-Enhancing Substance Use: A Population-Based Twin Study in Young Adult Men

Twin Research and Human Genetics ◽

10.1375/twin.9.3.431 ◽

2006 ◽

Vol 9 (3) ◽

pp. 431-437 ◽

Cited By ~ 3

Author(s):

Anu Raevuori ◽

Anna Keski-Rahkonen ◽

Richard J. Rose ◽

Aila Rissanen ◽

Jaakko Kaprio

Keyword(s):

Substance Use ◽

Environmental Factors ◽

Twin Study ◽

Genetic Factors ◽

Population Based ◽

Tetrachoric Correlation ◽

Polychoric Correlation ◽

Adult Men ◽

Genetic And Environmental Factors ◽

Best Fit

AbstractIn the population-based FinnTwin16 study, proportions of genetic and environmental factors contributing to muscle dissatisfaction and muscle-enhancing substance use were assessed in 319 pairs of twin brothers: 141 monozygotic (MZ) and 178 dizygotic (DZ) pairs. In addition there were 86 twin individuals from pairs in which only one co-twin responded. Of all respondents, 30% experienced high muscle dissatisfaction. The corresponding proportion of muscle-enhancing substance use was 10%. The subjects were similar in age (23.8 years, 95% confidence interval [CI] 23.76–23.84), body mass index (23.7, 95% CI 23.5–23.9), and waist circumference (84.5 cm, 95% CI 83.7–85.2), independent of their muscle dissatisfaction or muscle-enhancing substance use status and independent of their zygosity. The MZ polychoric correlation for muscle dissatisfaction was .39 (95% CI .17–.58) and .27 for DZ pairs (95% CI .07–.46). The MZ tetrachoric correlation for muscle-enhancing substance use was .65 (95% CI .28–.87) and .56 for DZ pairs (95% CI .26–.78). The AE model, where additive genetic factors (A) accounted for 42% (95% CI .23–.59) and unique environmental factors (E) 58% (95% CI .41–.77) of the liability, provided the best fit for muscle dissatisfaction. The CE model, where common environmental factors (C) accounted for 60% (95% CI .37–.77) and unique environmental factors (E) 40% (95% CI .23–.63) of the liability, provided the best fit for muscle-enhancing substance use. Both genetic and unique (nonfamilial) environmental factors are involved in muscle dissatisfaction in the population. Nongenetic factors (both familial and non-familial) appear to best explain the use of muscle-enhancing substances.

Download Full-text

Risk Factors Influencing Smoking Behavior: A Turkish Twin Study

Twin Research and Human Genetics ◽

10.1017/thg.2014.43 ◽

2014 ◽

Vol 17 (6) ◽

pp. 563-573 ◽

Cited By ~ 5

Author(s):

Sevgi Yurt Öncel ◽

Danielle M. Dick ◽

Hermine H. Maes ◽

Fazil Alıev

Keyword(s):

Environmental Factors ◽

Nicotine Dependence ◽

Twin Study ◽

Genetic Factors ◽

Structural Equation Models ◽

Environmental Influence ◽

Smoking Behavior ◽

Smoking Initiation ◽

Smoking History ◽

Shared Environmental Influence

Aim: In this study, we introduce the first twin study in Turkey, focusing on smoking behavior, and laying the foundation to register all twins born in Turkey for research purposes. Using Turkish twins will contribute to our understanding of health problems in the context of cultural differences. Materials and methods: We assessed 309 twin pairs (339 males and 279 females) aged between 15 and 45 years living in the Kırıkkale and Ankara regions of Turkey, and administered a health and lifestyle interview that included questions about smoking status and smoking history. We analyzed the data using descriptive statistics, t-tests, chi-square tests, and bivariate and multivariate clustered logistic regression. In addition, we fit bivariate Structural Equation Models (SEM) to determine contributions of latent genetic and environmental factors to smoking outcomes in this sample. Results: One hundred seventy-eight participants (28.8%) were identified as smokers, smoking every day for a month or longer, of whom 79.2% were males and 20.8% were females. Mean values for number of cigarettes per day and the Fagerstrom Test of Nicotine Dependence (FTND; Fagerstrom, 1978) score were higher in males than in females, and age of onset was earlier in males. There was a significant positive correlation between the FTND score and number of cigarettes smoked per day, and a significant negative correlation between both variables and age at onset of smoking. Our study showed that gender, presence of a smoking twin in the family, age, alcohol use, marital status, daily sports activities, and feeling moody all played a significant role in smoking behavior among twins. The twin analysis suggested that 79.5% of the liability to FTND was influenced by genetic factors and 20.5% by unique environment, while familial resemblance for smoking initiation was best explained by common environmental factors. Conclusions: Marked differences in the prevalence of smoking behavior in men versus women were observed for the Turkish population. Genetic analyses showed that common environmental factors primarily contributed to smoking initiation, while genetic factors explained a greater proportion of variance in liability to nicotine dependence. Our study shows higher heritability estimate of the FTND scores and higher shared environmental influence on smoking initiation for both males and females than reported in previous studies.

Download Full-text

Evidence for a Substantial Genetic Influence on Biochemical Liver Function Tests: Results from a Population-based Danish Twin Study

Clinical Chemistry ◽

10.1093/clinchem/47.1.81 ◽

2001 ◽

Vol 47 (1) ◽

pp. 81-87 ◽

Cited By ~ 56

Author(s):

Lise Bathum ◽

Hans Christian Petersen ◽

Jens-Ulrik Rosholm ◽

Per Hyltoft Petersen ◽

James Vaupel ◽

...

Keyword(s):

Alcohol Consumption ◽

Environmental Factors ◽

Liver Function ◽

Structural Equation ◽

Genetic Factors ◽

Liver Function Tests ◽

Population Based ◽

Function Tests ◽

Males And Females ◽

Danish Twin

Abstract Background: Biochemical liver function tests are widely used in the clinic and are some of the most frequently used tests in screening for diseases in older age groups. The aim of the present study was to estimate the relative importance of genetic and environmental factors to variations in these tests among the elderly. Methods: We conducted a survey among Danish twins, 73–102 years of age, identified in the population-based Danish Twin Registry. Among the 2749 individuals in the study population, an interview was conducted with 79%. From these, a blood sample was collected from 290 same-sex twin pairs, total of 580 subjects, within a 6-month period and analyzed for alanine aminotransferase (ALT), lactate dehydrogenase (LDH), γ-glutamyltransferase (GGT), bilirubin, and albumin. The interview included questions about alcohol consumption and body mass index (BMI; self-calculated height and weight). Heritability (proportion of the population variance attributable to genetic variation) was estimated using structural-equation analyses before and after correction for alcohol consumption and BMI. Results: Structural-equation analyses revealed a substantial heritability (35–61%) for the four biochemical liver function tests: ALT, GGT, LDH, and bilirubin. The remaining variation could be attributed to individuals’ nonfamilial environments. Adjustment for alcohol consumption and BMI had no influence on the heritability for ALT, GGT, LDH, and bilirubin. For albumin, two models fit equally well before adjustment for alcohol and BMI: a model including additive genetic and nonshared environmental factors (AE), and a model including shared and nonshared environmental factors (CE). After adjustment, the model including shared and nonshared environment was clearly the best fitting model. Conclusions: For both males and females, the effect of genetic factors on the biochemical liver function tests ALT, GGT, LDH, and bilirubin is substantial and accounts for one-third to two-thirds of the variation among individuals 73–102 years of age. The heritability is equal for males and females and does not change notably after controlling for alcohol consumption and BMI. For albumin, no major impact of genetic factors was found independent of BMI and alcohol consumption. An understanding of the genetic mechanisms underlying biochemical liver function tests among the very old may be of value in the interpretation of these tests in this age group.

Download Full-text

A Twin Study of the Influence of Smoking on Morbidity and Mortality

Acta geneticae medicae et gemellologiae ◽

10.1017/s1120962300025841 ◽

1970 ◽

Vol 19 (1-2) ◽

pp. 335-336 ◽

Cited By ~ 9

Author(s):

M. Hauge ◽

B. Harvald ◽

D. D. Reid

Keyword(s):

Public Health ◽

Cause Of Death ◽

Twin Study ◽

Genetic Factors ◽

General Pattern ◽

Tobacco Consumption ◽

Present Knowledge ◽

Harmful Effects ◽

Epidemiology And Public Health ◽

Danish Twin

The Danish Twin Register, which comprises all twins born in Denmark between 1870 and 1920, has been used for studies of selected problems in the field of epidemiology and public health. This report gives a survey of the preliminary results of an investigation of this type, which intends to amplify the present knowledge about the possible harmful effects of smoking on health, by taking advantage of a twin material which makes it possible to keep the genetic factors under control.A series of 762 MZ and same-sexed DZ twin pairs, which had their smoking habits mapped in 1959, has been followed continuously, and the mortality which has occurred in this group has been analysed in relation to tobacco consumption. Neither MZ nor DZ pairs showed any tendency to increased mortality in the heavier smoking cotwins. When the material was subdivided according to cause of death, no conspicuous exception from the general pattern was found, but the subgroups were relatively small.The distribution of selected diseases and symptoms, mainly of the cardiovascular and respiratory systems, was studied in this and a second series, followed since 1966, with a total of 1584 pairs.

Download Full-text

A Twin study of Individuals with both Schizophrenia and Alcoholism

The British Journal of Psychiatry ◽

10.1192/bjp.147.1.48 ◽

1985 ◽

Vol 147 (1) ◽

pp. 48-53 ◽

Cited By ~ 40

Author(s):

Kenneth S. Kendler

Keyword(s):

Environmental Factors ◽

Genetic Predisposition ◽

Twin Study ◽

Genetic Factors ◽

Substantial Evidence

SummarySubstantial evidence suggests that genetic factors contribute to the aetiology of both schizophrenia and alcoholism, when they occur alone. To examine the role of genetic factors in schizophrenia and alcoholism when they occur together in the same individual, the frequency of both conditions was investigated in the co-twins of 34 monozygotic (MZ) and 47 dizygotic (DZ) index twins with a diagnosis of both schizophrenia and alcoholism. Both disorders alone were significantly more common in the MZ than in the DZ co-twins, suggesting that individuals suffering from schizophrenia and alcoholism have a genetic predisposition to both disorders, which is of the same nature as that which causes the two when they occur alone. In the co-twins of the MZ index twins, the diagnoses of schizophrenia and alcoholism were uncorrelated, indicating that the specific environmental factors of causal importance in the two disorders are not closely related.

Download Full-text

Polygenic risk score and risk of monoclonal B-cell lymphocytosis in caucasians and risk of chronic lymphocytic leukemia (CLL) in African Americans

Leukemia ◽

10.1038/s41375-021-01344-9 ◽

2021 ◽

Author(s):

Geffen Kleinstern ◽

J. Brice Weinberg ◽

Sameer A. Parikh ◽

Esteban Braggio ◽

Sara J. Achenbach ◽

...

Keyword(s):

Environmental Factors ◽

B Cell ◽

Risk Score ◽

Genetic Factors ◽

Strong Predictor ◽

Lymphocytic Leukemia ◽

European Ancestry ◽

Polygenic Risk Score ◽

Polygenic Risk ◽

C Statistic

AbstractMonoclonal B-cell lymphocytosis (MBL) is a precursor to CLL. Other than age, sex, and CLL family-history, little is known about factors associated with MBL risk. A polygenic-risk-score (PRS) of 41 CLL-susceptibility variants has been found to be associated with CLL risk among individuals of European-ancestry(EA). Here, we evaluate these variants, the PRS, and environmental factors for MBL risk. We also evaluate these variants and the CLL-PRS among African-American (AA) and EA-CLL cases and controls. Our study included 560 EA MBLs, 869 CLLs (696 EA/173 AA), and 2866 controls (2631 EA/235 AA). We used logistic regression, adjusting for age and sex, to estimate odds ratios (OR) and 95% confidence intervals within each race. We found significant associations with MBL risk among 21 of 41 variants and with the CLL-PRS (OR = 1.86, P = 1.9 × 10−29, c-statistic = 0.72). Little evidence of any association between MBL risk and environmental factors was observed. We observed significant associations of the CLL-PRS with EA-CLL risk (OR = 2.53, P = 4.0 × 10−63, c-statistic = 0.77) and AA-CLL risk (OR = 1.76, P = 5.1 × 10−5, c-statistic = 0.62). Inherited genetic factors and not environmental are associated with MBL risk. In particular, the CLL-PRS is a strong predictor for both risk of MBL and EA-CLL, but less so for AA-CLL supporting the need for further work in this population.

Download Full-text

Decreased heritability and emergence of novel genetic effects on pulse wave velocity from youth to young adulthood

Scientific Reports ◽

10.1038/s41598-021-88490-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yisong Huang ◽

Shaoyong Su ◽

Harold Snieder ◽

Frank Treiber ◽

Gaston Kapuku ◽

...

Keyword(s):

Environmental Factors ◽

Pulse Wave Velocity ◽

Wave Velocity ◽

Young Adulthood ◽

Ethnic Differences ◽

Genetic Factors ◽

Pulse Wave ◽

Environmental Influences ◽

Genetic Effects ◽

Over Time

AbstractIncreased arterial stiffness measured by pulse wave velocity (PWV) is an important parameter in the assessment of cardiovascular risk. Our previous longitudinal study has demonstrated that carotid-distal PWV showed reasonable stability throughout youth and young adulthood. This stability might be driven by genetic factors that are expressed consistently over time. We aimed to illustrate the relative contributions of genetic and environmental factors to the stability of carotid-distal PWV from youth to young adulthood. We also examined potential ethnic differences. For this purpose, carotid-distal PWV was measured twice in 497 European American (EA) and African American (AA) twins, with an average interval time of 3 years. Twin modelling on PWV showed that heritability decreased over time (62–35%), with the nonshared environmental influences becoming larger. There was no correlation between the nonshared environmental factors on PWV measured at visit 1 and visit 2, with the phenotypic tracking correlation (r = 0.32) completely explained by shared genetic factors over time. Novel genetic influences were identified accounting for a significant part of the variance (19%) at the second measurement occasion. There was no evidence for ethnic differences. In summary, novel genetic effects appear during development into young adulthood and account for a considerable part of the variation in PWV. Environmental influences become larger with age for PWV.

Download Full-text

The Association Between Chronic Disease and Psychological Distress: An Australian Twin Study

Twin Research and Human Genetics ◽

10.1017/thg.2020.86 ◽

2020 ◽

Vol 23 (6) ◽

pp. 322-329

Author(s):

Jessica Tyler ◽

Janine Lam ◽

Katrina Scurrah ◽

Gillian Dite

Keyword(s):

Psychological Distress ◽

Chronic Disease ◽

Environmental Factors ◽

Twin Study ◽

Disease Status ◽

Adult Health ◽

Linear Regression Models ◽

Cross Sectional ◽

Genetic And Environmental Factors ◽

Distress Scale

AbstractThere is a commonly observed association between chronic disease and psychological distress, but many potential factors could confound this association. This study investigated the association using a powerful twin study design that can control for unmeasured confounders that are shared between twins, including genetic and environmental factors. We used twin-paired cross-sectional data from the Adult Health and Lifestyle Questionnaire collected by Twins Research Australia from 2014 to 2017. Linear regression models fitted using maximum likelihood estimations (MLE) were used to test the association between self-reported chronic disease status and psychological distress, measured by the Kessler Psychological Distress Scale (K6). When comparing between twin pairs, having any chronic disease was associated with a 1.29 increase in K6 (95% CI: 0.91, 1.66; p < .001). When comparing twins within a pair, having any chronic disease was associated with a 0.36 increase in K6 (95% CI: 0.002, 0.71; p = .049). This within-pair estimate is of most interest as comparing twins within a pair naturally controls for shared factors such as genes, age and shared lived experiences. Whereas the between-pair estimate does not. The weaker effect found within pairs tells us that genetic and environmental factors shared between twins confounds the relationship between chronic disease and psychological distress. This suggests that associations found in unrelated samples may show exaggerated estimates.

Download Full-text